1968 Colony Park 482

[cjshaker]

...and stay away from shop manuals from the 60’s lol....

They're good for torque specs on most things, but that's about it.

[FirstEliminator]

Why would the clearances change?

[blykins]

Did you measure them before?   Don’t expect plastigage to be anywhere close to accurate.

Also, different brands of  bearings will give different clearances.

[FirstEliminator]

Hi Brent,
    I did not measure the first set of bearings, back when it had the running noises. The dial bore gauges are new for this 2nd time of assembly. I pulled the front bearing cap just to see what plastigage would say. I did it twice and twice it came up close to what I measured. First time 3 tenths higher, second time 5 tenths higher. I wish I had another means of confirming the measurements.  But it wasn't run for long and only revved out a few times.  The old bearings are a bit shiny with some embedded debris. I would not attempt to reuse them.

    Why does this come out too tight? The bearing saddles, caps and both sides of the bearings were cleaned using coffee filters and brake clean then blown off with air. Dust free and dry.  Has anyone else had this problem? Is this a likely occurrence to run into? Is it because the bearings are manufactured to the spec of the factory Ford manual?

[FirstEliminator]

Another thought is, I have two other engines that are ready to assemble. I think I ought to put the main bearings in them and see how they measure out. A 460 into 545 and a 351w--stock.

[428 GALAXIE]

You have a micrometer with calibration stick?right?
You set bore gauge with that micrometer at room temperature and block is at that same temperature right?

If you check your bore gauge with micrometer and you get same results repeatedly I'll say you are close enough.

Sticking that bore gauge in some hole which should have diameter of xx but you don't  the exact won't tell you a thing.

[FirstEliminator]

  I guess my last post wasn't that direct on my intentions with the other two engines.  What I wanted to try was performing the same measurement proceedures on them to see if my technique and tools are measuring what would appear to be too tight like the 482. Or some other inconsistency. By measuring mains on other engines I hope to determine if the problem is with me or the 482.

[FirstEliminator]

Which brand of bearing tends to lean towards a looser clearance?

[Barry_R]

Need pictures of the old bearings - the wear pattern can reveal running clearances relative to the engines needs - if it "wants" more or less.

You are looking at tolerance stack up.  Common enough that we keep +.001 and -.001 bearings on the shelf to adjust on maybe 20% or 30% of our builds.  Every part whether a crankshaft, a bearing, or a fastener etc will have a target dimension and an acceptable range of variation. 

On many items the "perfect" dimension is not critical - you will never know if your valve cover gaskets are too thick by .020", and we measure oil pickup to pan clearances with a ruler and an OK range of an 1/8 of an inch.  Bearing clearance is among the most strict measurements in an engine - hydraulic lifter internals are even tighter.   You are looking at clearances which challenge the resolution accuracy of many inexpensive measuring tools, much less that of a string of plastic.  Fortunately engines are surprisingly forgiving if things are rationally close.  The process of inspection and measurement is often as important as the measurements themselves when it comes to identification of and addressing outliers.  Most manufacturers are really pretty darn good

A well meaning manufacturer with accurate controls might have the crankshaft journals all at the high end of the acceptable range, since its far easier to machine or polish a little off if it becomes necessary.  Many machine shops hone main saddles to the lower end of the accepted diameters to maximize bearing crush.  The bearing manufacturer has (in F-M's system) a target dimension +/- .0004" for accepted diameters.  If you get a crank that is .0003" big, a housing bore that is .0003" small, and a bearing that is .0003" tight - you have an assembly with inadequate clearance made of perfectly acceptable individual items.

[blykins]

Hi Brent,
    I did not measure the first set of bearings, back when it had the running noises. The dial bore gauges are new for this 2nd time of assembly. I pulled the front bearing cap just to see what plastigage would say. I did it twice and twice it came up close to what I measured. First time 3 tenths higher, second time 5 tenths higher. I wish I had another means of confirming the measurements.  But it wasn't run for long and only revved out a few times.  The old bearings are a bit shiny with some embedded debris. I would not attempt to reuse them.

    Why does this come out too tight? The bearing saddles, caps and both sides of the bearings were cleaned using coffee filters and brake clean then blown off with air. Dust free and dry.  Has anyone else had this problem? Is this a likely occurrence to run into? Is it because the bearings are manufactured to the spec of the factory Ford manual?

My guess is that the clearance was always tight if the main bearings are shiny and not looking well.   Plastigage just isn't accurate at all and most people don't know that it has to be refrigerated to even have any degree of accuracy whatsoever.   I haven't *seen* any plastigage in probably 18-19 years.   Unless you use it somehow for your transmission stuff, I'd chuck them in the trash now that you have the correct tools.   But I'll say this, even if the plastigage was reliable and your clearances were .0003-.0005" looser than what you're measuring, it's still too tight.   

Has anyone else had this problem?  Yep, all the time.   As Barry eluded to, our bearing shelves are plum full of standard, .001", X, Cleveland bearings, different brands of bearings, etc., because it happens on a rather consistent basis.  It's simply tolerance stack.   Sometimes, you can even change a brand of bearing and gain/lose tolerance.   Sometimes, things are loose and I don't have/can't get the right bearing, so I have the bearings coated.   Sometimes things are tight by a few tenths and I'll polish the journals up to make it consistent. 

[My427stang]

Some other things you can do to explain why it is tight

1 - Measure the the main cap bore with no bearing, if that spec is tight, the bearing will tighten up

2 - Get comfortable with the mike standard, and then use the same amount of "pressure" when tightening the mike to the crank.  By knowing the feel that the standard gets you to the proper number, you can tell if maybe you aren't tightening the micrometer enough on the journal.  I have one set that if I just use the ratchet it always feels loose to me.

3 - Just checking but, when you measure the journal, it really doesn't matter what it measures, although it's good info, just put the micrometer in a vice lightly or use a special stand to hold them to zero the tool.  The stand works better and is kinder to tools.  Be gentle when handling the micrometer after measuring and locking the barrel and setting up.  then set the bore gauge to zero, can't rush the zero setting, the more you do it, the more accurate you will be, all it takes is to be a bit off and your measurement is off

I typically do not see FE aftermarket cranks that tight very often, but we hit them with a polish after balancing.  That being said, the big jump on one of yours could be from error, goofy main bores, or a combination of things

As far as bearings no rules, but I have seen FMs to be a little looser, Clevites to be exactly what they say, and the same with TRW.  I haven't used enough Kings to have an opinion, the last set I got sits on the shelf, they were .001 bigger rod bearings that I thought I bought .001 smaller....they measured exactly what they said   I just ordered the wrong things LOL

[blykins]

What are you getting for main journal measurements?

I’m usually somewhere in the ballpark of  2.7488-2.7491...

[FirstEliminator]

Mains 1, 2, 4, 5 measure 2.7484. #3 measured 2.7485.

Just got back from. The hardware store with 600 and 1500 grit paper and metal polish. The crank looks o-k, but it would be a good idea to polish it before  it is run on the new bearings.  Polishing is also a good idea since a lumber yard went through the engine.

[blykins]

Ok, you need to come up with a game plan...

The sandpaper and metal polish won't do anything except make the journals shiny.  Also, what you do may be for naught if you have to have the crank "adjusted".  When you use a crank polisher, it's usually either a lathe or a polishing-specific machine, which turns the crankshaft in normal rotation.  There is a hand-held motor that has a 3'-4' belt that's about an inch wide.  They will take material off if you do it this way, but whomever is operating it has to be very careful as it's possible to taper the journals or make them out of round.

At this point, I would double-check all of your measurements.  Your crank journals aren't on the big side, so I would check the housing bore next and see what's going on. 

If you don't really come to any conclusion except for the tolerances are stacked against you, then you need a game plan, because .0015" of main bearing clearance won't work.   If I were in your spot, I would approach it in one of two different ways:

1.  If you have a reputable crank grinder available to you, I'd take the crank to him and give him a measurement to shoot for.  Most crank grinders who are competent can grind .001-.0015" accurately off of journals. 

2.  Buy a set of Federal Mogul 146MX bearings.  File the tangs off.  Check the clearances with those.  If you come in at around .0025", I'd likely call it a day and put it together.  If you want to get anal about it, you could have a crank grinder/machinist polish a few more tenths off.    The 146 bearings are Cleveland bearings.  There are no "X" bearings for a standard FE main journal, so it's possible to use a Cleveland bearing since the journal diameters and widths are the same.  Only issue is that the locating tangs are on opposite sides, so you have to remove them. 

[Barry_R]

I still want to see pictures of the old main bearings